Ball valves are generally known in the art and used in a variety of applications ranging from liquid to gas flow control. A typical ball valve includes a housing, also often referred to as a valve body, that has an internal cavity and an inlet and an outlet in fluid communication with the internal cavity. A flow path extends from the inlet, through the cavity, and through the outlet.
A spherical valve member is positioned in the flow path within the internal cavity of the housing. The valve member has a passageway extending entirely through the center of the valve member. A variety of seals can be employed within the internal cavity and adjacent the valve member to restrict flow through the passageway of the valve member, and prevent fluid from freely flowing around the valve member that would otherwise cause leakage.
The passageway through the valve member is selectively alignable with the flow path extending through the housing. A stem extends through the wall of the housing and is mechanically coupled to the valve member such that rotation of the stem results in a like rotation in the valve member. As such the valve member within the housing is selectively alignable with the flow path via rotation of the valve stem from outside of the housing.
Partial or complete alignment of the passageway with the flow path will allow fluid to flow from the inlet to the outlet of the housing. When this is so, the valve is said to be in a partial or fully open position, respectively. Complete misalignment of the passageway with the flow path will prevent fluid to flow from the inlet to the outlet. When this is so, the valve is said to be in a closed position. As such, the range of positions of a typical ball valve are often categorized as fully open, partially open, or fully closed.